Gender-Specificity of Initial and Controlled Visual Attention to Sexual Stimuli in Androphilic Women and Gynephilic Men

Research across groups and methods consistently finds a gender difference in patterns of specificity of genital response; however, empirically supported mechanisms to explain this difference are lacking. The information-processing model of sexual arousal posits that automatic and controlled cognitive processes are requisite for the generation of sexual responses. Androphilic women’s gender-nonspecific response patterns may be the result of sexually-relevant cues that are common to both preferred and nonpreferred genders capturing attention and initiating an automatic sexual response, whereas men’s attentional system may be biased towards the detection and response to sexually-preferred cues only. In the present study, we used eye tracking to assess visual attention to sexually-preferred and nonpreferred cues in a sample of androphilic women and gynephilic men. Results support predictions from the information-processing model regarding gendered processing of sexual stimuli in men and women. Men’s initial attention patterns were gender-specific, whereas women’s were nonspecific. In contrast, both men and women exhibited gender-specific patterns of controlled attention, although this effect was stronger among men. Finally, measures of attention and self-reported attraction were positively related in both men and women. These findings are discussed in the context of the information-processing model and evolutionary mechanisms that may have evolved to promote gendered attentional systems.     

Synthesis of myelin glycosphingolipids (galactosylceramide and galactosyl(3-O-sulfate)ceramide (sulfatide)) by cloned cell lines derived from mouse neurotumors

Clonal cell lines derived from both spontaneous and chemically induced rat and mouse brain tumors were screened for their ability to incorporate H232SO4 into galactosyl(3-O-sulfate)ceramide (sulfatide). High levels of 35SO4 incorporation into sulfatide were found only in two of the mouse cell lines studied (G26-20 and -24). Tumors produced by subcutaneous injection of these cell lines into C57BL/6 mice were also unique in that they contained high levels of both sulfatide and galactosylceramide. The synthesis of large amounts of sulfatide and galactosylceramide by a clonal cell line of neurological origin suggests that the original tumor was of oligodendrocyte or Schwann cell origin. In common with a large number of mouse and rat astrocyte cell strains and their derived tumors, these glial cells lacked the ability to synthesize gangliosides such as monosialotetraglycosylceramide and disialotetraglycosylceramide (as judged by analytical and [3H]GlcNH2 incorporation studies). This appears to be a unique characteristic of neuroblastoma-derived cell strains such as N18, NB2a, and NB41A.     

Thermoregulation and heterothermy in some of the smaller flying foxes (Megachiroptera) of New Guinea

Summary Body temperature, heterothermy, oxygen consumption, heart rate, and evaporative water loss were studied in four species of flying foxes (Megachiroptera), Dobsonia minor, Nyctimene major, Nyctimene albiventer, and Paranyctimene raptor, from the vicinity of Madang on the north coast of New Guinea.The thermoregulatory response of D. minor resembled that of most other placental mammals weighing 80 to 100 g. Body temperatures were relatively stable at ambient temperatures between 5 and 34°. The mean oxygen consumption at rest between 30 and 35° was 1.26 cc O₂ (g·hr)^–1. At ambient temperatures between 5 and 35° evaporative water loss averaged 4.5 mg (g·hr)^–1 and increased sharply at higher temperatures. When subjected to heat stress the animals panted, salivated, and licked the wings, belly, and uropatagium. At temperatures above 38° the ratio of heat lost through evaporation to heat production exceeded 1. Minimal heart rates in resting animals near thermal neutrality were approximately 275/min.In those parameters measured, N. major which weighed about 80 g resembled D. minor. Nyctimene albiventer and P. raptor weigh less than 30 g and are among the smallest of the flying foxes. Each shows both homeothermic and heterothermic patterns of response. At an ambient temperature of 35° the minimal oxygen consumption of homeothermic N. albiventer and P. raptor were 1.43 and 1.38 cc O₂ (g·hr)^–1, respectively. Oxygen consumption of homeothermic N. albiventer at 25°, 2.59 cc O₂ (g.hr)^–1, was almost quadruple that of torpid animals at the same temperature. During the daytime both N. albiventer and P. raptor characteristically allowed their body temperatures to fall to near 25°. Both readily aroused from the hypothermic state through physiological means. Heart rates of homeothermic N. albiventer resting at 35° ranged from 312 to 326/min while those of animals torpid at 25° were 88 to 96/min.The capacity for heterothermy has not previously been demonstrated in any members of the Megachiroptera, but our data indicate that it can occur on a daily basis in N. albiventer and P. raptor. This capacity appears to be related to size since it occurs in none of the larger flying foxes so far studied.The data presently available indicate that the relation of body weight to standard metabolism in the Megachiroptera is similar to that of the other placental mammals. In the species we studied, thermal conductances were higher, and heart rates, lower than predicted for mammals of their sizes.These studies were carried out during the 1969 Alpha Helix Expedition to New Guinea and were supported in part by grants GB-5139, GB-3656, and GB-8445 from the U. S. National Science Foundation.     

Secondary (iso)BAs cooperate with endogenous ligands to activate FXR under physiological and pathological conditions

IsoBAs, stereoisomers of primary and secondary BAs, are found in feces and plasma of human individuals. BA signaling via the nuclear receptor FXR is crucial for regulation of hepatic and intestinal physiology/pathophysiology. Aim: Investigate the ability of BA-stereoisomers to bind and modulate FXR under physiological/pathological conditions. Methods: Expression-profiling, luciferase-assays, fluorescence-based coactivator-association assays, administration of (iso)-BAs to WT and cholestatic mice. Results: Compared to CDCA/isoCDCA, administration of DCA/isoDCA, UDCA/isoUDCA only slightly increased mRNA expression of FXR target genes; the induction was more evident looking at pre-mRNAs. Notably, almost 50% of isoBAs were metabolized to 3-oxo-BAs within 4 h in cell-based assays, making it difficult to study their actions. FRET-based real-time monitoring of FXR activity revealed that isoCDCA>CDCA stimulated FXR, and isoDCA and isoUDCA allowed fully activated FXR to be re-stimulated by a second dose of GW4064. In vivo co-administration of a single dose of isoBAs followed by GW4064 cooperatively activated FXR, as did feeding of UDCA in a background of endogenous FXR ligands. However, in animals with biliary obstruction and concomitant loss of intestinal BAs, UDCA was unable to increase intestinal Fgf15. In contrast, mice with an impaired enterohepatic circulation of BAs (Asbt?/?, Ostα?/?), administration of UDCA was still able to induce ileal Fgf15 and repress hepatic BA-synthesis, arguing that UDCA is only effective in the presence of endogenous FXR ligands. Conclusion: Secondary (iso)BAs cooperatively activate FXR in the presence of endogenous BAs, which is important to consider in diseases linked to disturbances in BA enterohepatic cycling.